In the United States, traditional lecture-based teaching methods have not effectively met the needs of diverse learners in higher education (HE). This is particularly problematic as diversity is increasing amongst learners, including those with diverse racial, ethnic, gender, academic, and emotional backgrounds. The predominance of the two-tiered system and over reliance on the lecture-based model in foreign language (FL) classrooms has resulted in higher attrition rates and lower academic achievement and retention rates. The root of the problem is the need for more differentiated instruction (DI) and the predominance of a One-Size-Fits-All approach in FL college classrooms. This research focuses on FL professors' perceptions, experiences, and willingness to attend professional development on differentiated instruction. Two theoretical frameworks guide this research: Tomlinson's (1999) theory, which emphasizes the need for differentiated instruction to meet the needs of all learners, and Krashen's (1982) theory on how foreign languages are acquired. Data was collected through one-to-one telephone interviews with eight professors from three universities in the United States and then analyzed using thematic coding and analysis (Saldana, 2021). Professors were asked about their experiences and perceptions of implementing differentiated instruction. Findings revealed that professors' perceptions and implementation of differentiated instruction varied, diversity was present in all classrooms, and professional development on differentiated instruction was sought. However, they also mentioned that they lacked sufficient knowledge of differentiated strategies and required more time and incentives to implement them effectively. This qualitative study demonstrates that professors implementing differentiated instruction can help students succeed in FL HE classrooms, leading to positive change. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]